Power bank



FIG. 1 is a front elevational view of a power bank showing my new design;

FIG. 2 is a rear elevational view thereof;

FIG. 3 is a left side view thereof;

FIG. 4 is a right side view thereof;

FIG. 5 is a top plan view thereof;

FIG. 6 is a bottom plan view thereof;

FIG. 7 is a perspective view thereof; and,

FIG. 8 is another perspective view thereof.

The broken lines present in the figures are included for the purpose of illustrating portions of the article which form no part of the claimed design. 

CLAIM The ornamental design for a power bank, as shown and described. 